Glyceraldehyde-3-phosphate dehydrogenase (NADP+)

Glyceraldehyde-3-phosphate dehydrogenase (NADP+) (EC 1.2.1.9) (GAPN) is an enzyme that irreversibly catalyzes the oxidation of glyceraldehyde-3-phosphate (GAP) to 3-phosphoglycerate (3-PG or 3-PGA) using the reduction of NADP+ to NADPH. GAPN is used in a variant of glycolysis that conserves energy as NADPH rather than as ATP. The NADPH and 3-PG can then be used for synthesis. The most familiar variant of glycolysis uses glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoglycerate kinase to produce ATP. GAPDH is phosphorylating. GAPN is non-phosphorylating.

Glyceraldehyde-3-phosphate dehydrogenase (NADP+)
Identifiers
EC no.	1.2.1.9
CAS no.	9028-92-6
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

GAPN was reported first by Rosenberg and Arnon in 1954.^[1] It has been found in plants, algae, and bacteria.^[2]

Reactions

Glyceraldehyde-3-phosphate dehydrogenase (NADP+) catalyzes

GAP + NADP⁺ + H₂O → 3-PG + NADPH + H⁺

Glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase catalyze

GAP + NAD⁺ + P_i ⇌ 1,3-bisphosphoglycerate + NADH + H⁺

1,3-bisphosphoglycerate + ADP ⇌ 3-PG + ATP

Usually [NADPH] / [NADP⁺] >> 1 >> [NADH] / [NAD⁺].

See also

• Pentose phosphate pathway